8. directed numbers
TRANSCRIPT
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DIRECTED NUMBERS
Objectives: Add, subtract, multiply and divide directed numbers
Grade 8
Monica Roshani Rupasinghe
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Directed Numbers
👉Numbers which has a direction as
well a size are called directed numbers.
👉They can be negative or positive
👉 Positive + sign
Negative - sign
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Visualising negatives with a number line
-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6
For any addition/subtraction of numbers, you should ALWAYSvisualise a number line. How would we visualise the following?
Click>
Click>
Click>
Click>
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Eg 1 : Temperature starts at 4°C & falls by 4°C
Eg 2 : Temperature starts at -2°C & rise by 5°C
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Exercise1 ( e3 pg 52 / e4 pg 58 / e5 pg 56 )
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Exercise1 ( e3 pg 52 / e4 pg 58 / e5 pg 56 )
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Addition & Subtraction 👉 If the signs are SAME , we add the numbers ( +,+ or -,-)
👉 If the signs are DIFFERENT , we Subtract the numbers
âś… Subtract the smaller number by larger number
âś… Sign in front of the Larger number is the sign of the result
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Example
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Test Your Understanding
Copy and complete the following.
What is ?
a
b
c
d
e
f
g
h
N
???
?????
?
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Multiplication & Division
👉 If the signs are SAME , the result is Positive
👉 If the signs are DIFFERENT , the result is Negative
đź“Ś Division
đź“Ś Multiplication
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Example
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Use of Brackets
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Adding/subtracting negative numbers
What is the answer. How could we show it?
What is the answer. How could we show it?
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✏
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Quick fire Examples
1. ?
?
?
?
?
?
?
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RED ORANGE GREEN BLUE
Use your diary coloured cards to vote for the correct answer in each question.
(Use the front of your diary for blue)
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Calculate:
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Calculate:
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Calculate:
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Calculate:
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Calculate:
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Calculate:
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